The except Ii Default Reasoning System Preliminary Report

Preface Except II is a system that supports several kinds of reasoning ranging from basic deduction and abduction to high-level forms such as diagnosis, connguration, and induction. Its main and characteristic feature that enables this is default reasoning. Default reasoning is an attempt to handle defeasible inferences properly and to provide qualitative, argument-based methods for deciding between connicting arguments. Thus, Except II does not only allow to express heuristic rules of thumb, it is also able to retract rules in presence of better advice. In this aspect, the default reasoning system Except II is superior to so called expert system tools that are based on production rules. Production rules provide only simple and non-declarative forms of connict resolution without the possibility of subsequent revision (by the user or other rules). Nevertheless, Except II proots from techniques developed in this area. In addition to defaults, Except II handles a large subclass of rst-order logic, namely clauses restricting variables in their conclusions to those occurring in their condition-parts. This language is suucient for a lot of applications, enables reasoning by cases in contrast to Prolog, but does not require all the work of a general theorem prover. Due to these features, Except II is interesting for all people who are looking for more transparent tools to do applications such as diagnosis or connguration. For this purpose, this report contains a user manual, as well as examples that demonstrate how default reasoning is applied practically. Additionally, this report provides some technical information about Except II. Thus, people interested in non-monotonic reasoning or automated deduction may gain some insights how to implement a default prover. Last, but not least, this report may convince traditional expert system builders to use more advanced and well-founded tools. As mentioned above, this report is divided into three parts. The rst part fo-cuses on the usage of the basic features of Except II. It introduces the logical language, defaults, as well as queries for deductive, abductive, and non-monotonic proofs. Technical information about architecture, control, inference, database handling , reason maintenance, and argument synthesis of Except II is included in the second part. In the last part, we show how more advanced constructs such as classes, components, and constraints can be be expressed in the basic language. Furthermore , we encode some examples for higher-level forms of reasoning: diagnosis of an electronic circuit, connguration of ooce equipment including some geometrical …